Immunogene Therapy for Murine Melanoma Using Recombinant Adenoviral Vectors Expressing Melanoma-Associated Antigens

Abstract

Adenoviral vectors expressing tumor-associated antigens can be used to evoke a specific immune response and inhibit tumor growth. In this study, we tested the efficacy of adenoviral vectors encoding human gp100 (Ad2/hugp100), murine gp100 (Ad2/mugp100), or murine TRP-2 (Ad2/muTRP-2) for their ability to elicit a specific cellular immune response and inhibit the growth of B16 melanoma tumor cells in the mouse. C57BL/6 mice were immunized with Ad2/hugp100, Ad2/mugp100, or Ad2/muTRP-2 either 2 weeks prior to B16-F10 tumor challenge (prophylactic treatment) or 3 days after tumor challenge (active treatment). Ad2/hugp100 and Ad2/muTRP-2 administered to two or more intradermal (i.d.) sites inhibited subsequent subcutaneous tumor growth in > or = 80% of the mice and elicited an antigen-specific cytotoxic T lymphocyte response, whereas other administration routes were not as effective. Ad2/mugp100 administered to two i.d. sites did not inhibit tumor growth or provoke cellular immunity. Immunization was less effective with active treatment where tumor growth was not significantly inhibited by a single dose of either Ad2/muTRP-2 or Ad2/hugp100. However, increasing the number of intradermal immunization sites and the number of doses resulted in progressive improvements in protection from tumor growth in the active treatment model. In conclusion, breaking host tolerance to elicit protective immunity by using adenoviral vectors expressing melanoma-associated antigens is dependent upon the choice of antigen, the site of administration, and the number of doses. These observations provide insights into the clinical applicability of adenoviral vaccines for immunotherapy of malignant diseases.

Dendritic cells transduced with gp100 gene by RGD fiber-mutant adenovirus vectors are highly efficacious in generating anti-B16BL6 melanoma immunity in mice

“…However, mice vaccinated with viral vectors encoding murine gp100 do not develop measurable murine gp100-specific immunity, and are apparently tolerant to murine gp100. 26,27 In contrast, immunization with human gp100-expressing viral vectors can overcome self-tolerance to gp100 in C57BL/6 mice because this approach induces human gp100-specific and also murine B16 melanomacrossreactive T-cell responses. 26,27 Furthermore, immunization with DCs transduced ex vivo with human gp100 gene using conventional Ad generates more effective anti-B16 melanoma immunity than in vivo direct injection of human gp100-expressing Ad.…”

Enabling topical immunization via microporation: a novel method for pain-free and needle-free delivery of adenovirus-based vaccines

“…We were also able to generate protective anti-tumor immunity and auto-immune vitiligo using one or two administrations of 1 Â 10 7 pfu rdAd in the CT-26.CL25 and B16 tumor models, respectively, consistent with previous reports where doses generally ranged between 10 8 and 10 9 pfu per immunization. 3,18,[23][24][25] Thus, with our current passive approach we can employ similar virus doses as those using intradermal and subcutaneous routes. We expect that the active delivery methods that we are developing will further increase the potency of the microporation technology.…”

“…One antigen, TRP-2, has displayed promising activity in pre-clinical models. 3,18,19 AdhTRP-2 (5 Â 10 6 pfu/ml) was applied two times to either intact or microporated skin 21 days apart followed by a challenge with B16 Figure 4 Increased magnitude and rate of seroconversion following topical administration of genetic vaccine to microporated skin. Adb-gal (5 Â 10 6 pfu/ml) was applied to both microporated and intact skin.…”

“…Indeed, several recent publications investigating genetic vaccines have demonstrated that the intradermal route of administration yielded the highest efficacy. [2][3][4] However, efficient intradermal injection is both difficult and painful and is hampered by the short depth of the skin limiting the volume of the inoculum and, quite often, the payload is delivered to the subcutaneous region rather than the dermis.…”

“…2,11 RdAds exhibit a number of properties that make them appealing vectors for genetic vaccination: (1) they elicit robust cellular and humoral responses, (2) they can readily accommodate up to 8 kb of foreign DNA, (3) they are easily manipulated and propagated using basic molecular biology and tissue culture techniques and (4) they have not been associated with disease in immunocompetent hosts. 12 Despite the high efficacy of rdAd vaccines delivered intradermally, 2,3 reproducibly delivering materials to the skin using a standard needle and syringe is technically challenging. Topical administration should prove less complicated and, indeed, previous reports have demonstrated that rdAds can successfully immunize mice following topical application to de-cornified skin.…”